ID: Similar to some forms of the variable A.comariana and A.laterana. A.laterana averages larger (ws: 17-21mm fw 7-9mm). May be separable from A.comariana (at least) by habitat, A.comariana being a lowland species. All references refer to A.caledoniana as having a narrower forewing with a more acute apex and BTM states that the species may be 'readily distinguished' by this feature. MBGBI 5.2 gives forewing length:breadth ratios for A.caledoniana/laterana/comariana as 2.5x, 2x and 1.5x respectively; and termen to costa angles of 60°, 70° and 80° respectively. However, I have found these distinctions entirely unconvincing. By eyeball the termen to costa angle does not look consistently different between the species and measurement of the angle is hampered by the costa being somewhat curved and the termen somewhat sinuate, making it a bit too much a matter of judgment where you put your protractor to secure sufficient accuracy. Forewing length:breadth ratios measured from specimens in my photo collection, using only detached flattened wings, (number of specimens in parenthesis): A.caledoniana 2.8 - 3.0 (5), A.laterana 2.6 - 3.0 (11), A.comariana 2.8-3.0 (4) - suggesting to me that the figures quoted in MBGBI5.1 are complete nonsense.Male genitalia: The aedeagus of A.laterana contains 1 long and ~3 shorter cornuti and this feature readily distinguishes this species. The aedeagus of A.comariana contains no cornuti. Pierce and Metcalfe states that the aedeagus of A.caledoniana has 2-4 extremely fine spines - which are not visible either in their own drawing (Plate VII) or in the images of this species at Moth Dissection, but they are drawn in the illustration in MBGBI5.1 (fig.9, p199). MBGBI5.1 states that the ventral excision in the valva is "the most salient character for separating the species" - but it doesn't describe the difference. In the illustrations in MBGBI5.1 the ventral margin of the valva medial to the excision is drawn with a more shallow curve as it enters the excision in A.comariana than in A.caledoniana - this distinction cannot be confirmed either by comparing images of the two species at Moth Dissection or by comparing my images of the two species. This leaves us with no reliable way of distinguishing male A.caledoniana from similar A.comariana apart from habitat.Female genitalia:A.laterana lacks a signum in the bursa copulatrix and possesses a small triangular smudge of sclerotisation in the introitus vaginae. A.comariana possesses a small signum in the bursa and lacks any sclerotisation in the introitus. In the illustrations in MBGBI5.1, A.caledoniana is similar to A.comariana for both these features, but Pierce & Metcalfe state (I think incorrectly) that A.caledoniana lacks a signum. In the illustrations in MBGBI5.1 these two species differ in the shape of the anterior margin of the sterigma - both show a central convexity - in A.comariana the convexity is relatively steep and narrow (about as broad as the introitus); in A.caledoniana the convexity is relatively broad and shallow (~2x as broad as the introitus). This difference cannot be confirmed by comparing images of the two species at Moth Dissection. So, again, we are left with habitat as the only means of distinguishing female A.caledoniana from similar A.comariana.